LIS3L02AQ3
MEMS INERTIAL SENSOR: 3-Axis - 2g/6g LINEAR ACCELEROMETER
1
Features
2.4V TO 3.6V SINGLE SUPPLY OPERATION LOW POWER CONSUMPTION 2g/6g USER SELECTABLE FULL-SCALE BETTER THAN 0.5mg RESOLUTION OVER 100Hz BANDWIDTH EMBEDDED SELF TEST AND POWER DOWN OUTPUT VOLTAGE, OFFSET AND SENSITIVITY RATIOMETRIC TO THE SUPPLY VOLTAGE HIGH SHOCK SURVIVABILITY ECO-PACK COMPLIANT
Figure 1. Package
Q FN - 4 4
Table 1. Order Codes
Part Number LIS3L02AQ3 LIS3L02AQ3TR Package QFN-44 QFN-44 Finishing TRAY TAPE & REEL
2
Description
The LIS3L02AQ3 is a low-power 3-Axis linear capacitive accelerometer that includes a sensing element and an IC interface able to take the information from the sensing element and to provide an analog signal to the external world. The sensing element, capable of detecting the acceleration, is manufactured using a dedicated process developed by ST to produce inertial sensors and actuators in silicon. The IC interface is manufactured using a standard CMOS process that allows high level of integration to design a dedicated circuit which is trimmed to better match the sensing element characteristics. The LIS3L02AQ3 has a user selectable full scale of Figure 2. Block Diagram
X+ Y+ Z+
2g, 6g and it is capable of measuring accelerations over a bandwidth of 1.5 KHz for all axes. The device bandwidth may be reduced by using external capacitances. A self-test capability allows to check the mechanical and electrical signal path of the sensor. The LIS3L02AQ3 is available in plastic SMD package and it is specified over an extended temperature range of -40C to +85C. The LIS3L02AQ3 belongs to a family of products suitable for a variety of applications: Mobile terminals Gaming and Virtual Reality input devices Free-fall detection for data protection Antitheft systems and Inertial Navigation Appliance and Robotics
Routx CHARGE AMPLIFIER S/H
Voutx
a
ZYX-
MU X
DEMUX
Routy S/H
Vouty
Routz S/H
Voutz
SELF TEST
REFERENCE
TRIMMING CIRCUIT
CLOCK
May 2005
Rev. 2 1/13
LIS3L02AQ3
Table 2. Pin Description
N 1 to 3 4 5 6 7 8 9-13 14 15 16 17-18 19 20 21 22-23 24-25 26 27 28 29-44 Pin NC GND Vdd Vouty ST Voutx NC PD Voutz FS Reserved Reserved Reserved NC Reserved NC Reserved Reserved Reserved NC Internally not connected 0V supply Power supply Output Voltage, y-channel Self Test (Logic 0: normal mode; Logic 1: Self-test) Output Voltage, x-channel Internally not connected Power Down (Logic 0: normal mode; Logic 1: Power-Down mode) Output Voltage, z-channel Full Scale selection (Logic 0: 2g Full-scale; Logic 1: 6g Full-scale) Leave unconnected Leave unconnected Leave unconnected Internally not connected Leave unconnected Internally not connected Connect to Vdd or GND Leave unconnected or connect to Vdd Leave unconnected or connect to GND Internally not connected Function
Figure 3. Pin Connection (Top view)
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC NC NC NC NC
Z
1 Y
NC NC GN D Vdd Vo u t y ST
LIS3L02AQ3
Reserved Reserved Reserved NC NC Reserved
X
Vo u t x NC NC
DIRECTION OF THE DETECTABLE ACCELERATIONS
NC
Voutz
Reserved
Reserved
Reserved
Reserved
2/13
Reserved
NC
NC
PD
FS
NC
LIS 3L02AQ3
Table 3. Mechanical Characteristics1 (Temperature range -40C to +85C) All the parameters are specified @ Vdd =3.3V, T=25C unless otherwise noted
Symbol Ar Parameter Acceleration Range
3
Test Condition FS pin connected to GND FS pin connected to Vdd
Min. 1.8 5.4 Vdd/510% Vdd/1510%
Typ.2 2.0 6.0 Vdd/5 Vdd/15 0.01
Max.
U ni t g g
So SoDr Voff OffDr NL
Sensitivity4 Sensitivity Change Vs Temperature Zero-g Level4 Zero-g Level Change Vs Temperature Non Linearity5
Full-scale = 2g Full-scale = 6g Delta from +25C T = 25C Delta from +25C Best fit straight line Full-scale = 2g X, Y axis Best fit straight line; Full-scale = 2g Z axis
Vdd/5+10% Vdd/15+10%
V/g V/g %/C
Vdd/2-6%
Vdd/2 0.8 0.3
Vdd/2+6%
V mg/C
1.5
% FS
0.6
2
% FS
CrossAx Cross-Axis6 An Vt Acceleration Noise Density Self Test Output Voltage Change7,8,9 Vdd=3.3V; Full-scale = 2g T = 25C Vdd=3.3V Full-scale = 2g X axis T = 25C Vdd=3.3V Full-scale = 2g Y axis T = 25C Vdd=3.3V Full-scale = 2g Z axis Fres Top Wh Sensing Element Resonance Frequency10 Operating Temperature Range Product Weight all axes -2 0
2 50 -50
4
% g/
Hz
-100
mV
20
50
100
mV
20
50
100
mV
1.5 -4 0 0.2 +85
KHz C gram
Notes: 1. The product is factory calibrated at 3.3V. The device can be powered from 2.4V to 3.6V. Voff, So and Vt parameters will vary with supply voltage. 2. Typical specifications are not guaranteed 3. Guaranteed by wafer level test and measurement of initial offset and sensitivity 4. Zero-g level and sensitivity are essentially ratiometric to supply voltage 5. Guaranteed by design 6. Contribution to the measuring output of the inclination/acceleration along any perpendicular axis 7. Self test "output voltage change" is defined as Vout(Vst=Logic1)-Vout(Vst=Logic0) 8. Self test "output voltage change" varies cubically with supply voltage 9. When full-scale is set to 6g, self-test "output voltage change" is one third of the specified value 10.Minimum resonance frequency Fres=1.5KHz. Sensor bandwidth=1/(2**110K*Cload) with Cload>1nF.
3/13
LIS3L02AQ3
Table 4. Electrical Characteristics1 (Temperature range -40C to +85C) All the parameters are specified @ Vdd =3.3V, T=25C unless otherwise noted
Symbol Vdd Idd Parameter Supply Voltage Supply Current mean value PD pin connected to GND rms value PD pin connected to Vdd Logic 0 level Logic 1 level Rout Cload Ton Top Output Impedance Capacitive Load Drive3 Turn-On Time at Exit From Power Down Mode Operating Temperature Range Cload in F -40 0 2.2 80 320 550*Cload +0.3 +85 110 Test Condition Min. 2.4 Typ.2 3.3 0.85 Max. 3.6 1.5 Unit V mA
IddPdn
Supply Current in Power Down Mode Self Test Input
2
5
A
Vst
0.8 Vdd 140
V V
k
pF ms C
Notes: 1. The product is factory calibrated at 3.3V. 2. Typical specifications are not guaranteed 3. Minimum resonance frequency Fres=1.5KHz. Sensor bandwidth=1/(2**110K*Cload) with Cload>1nF
3
Absolute Maximum Rating
Stresses above those listed as "absolute maximum ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device under these conditions is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. Table 5. Absolute Maximum Rating
Symbol Vdd V in APOW AUNP TSTG ESD Supply voltage Input Voltage on Any Control pin (FS, PD, ST) Acceleration (Any axis, Powered, Vdd=3.3V) Acceleration (Any axis, Not powered) Storage Temperature Range Electrostatic Discharge Protection Ratings Maximum Value -0.3 to 7 -0.3 to Vdd +0.3 3000g for 0.5 ms 10000g for 0.1 ms 3000g for 0.5 ms 10000g for 0.1 ms -40 to +125 2KV HBM 200V MM 1500V CDM C Unit V V
This is a ESD sensitive device, improper handling can cause permanent damages to the part. This is a mechanical shock sensitive device, improper handling can cause permanent damages to the part.
4/13
LIS 3L02AQ3
3.1 Terminology Sensitivity describes the gain of the sensor and can be determined by applying 1g acceleration to it. As the sensor can measure DC accelerations this can be done easily by pointing the axis of interest towards the center of the earth, note the output value, rotate the sensor by 180 degrees (point to the sky) and note the output value again thus applying 1g acceleration to the sensor. Subtracting the larger output value from the smaller one and dividing the result by 2 will give the actual sensitivity of the sensor. This value changes very little over temperature (see sensitivity change vs. temperature) and also very little over time. The Sensitivity Tolerance describes the range of Sensitivities of a large population of sensors. Zero-g level describes the actual output signal if there is no acceleration present. A sensor in a steady state on a horizontal surface will measure 0g in X axis and 0g in Y axis whereas the Z axis will measure +1g. The output is ideally for a 3.3V powered sensor Vdd/2 = 1650mV. A deviation from ideal 0-g level (1650mV in this case) is called Zero-g offset. Offset of precise MEMS sensors is to some extend a result of stress to the sensor and therefore the offset can slightly change after mounting the sensor onto a printed circuit board or exposing it to extensive mechanical stress. Offset changes little over temperature - see "Zero-g level change vs. temperature" - the Zero-g level of an individual sensor is very stable over lifetime. The Zero-g level tolerance describes the range of zero-g levels of a population of sensors. Self Test allows to test the mechanical and electrical part of the sensor. By applying a digital signal to the ST input pin an internal reference is switched to a certain area of the sensor and creates a defined deflection of the moveable structure. The sensor will generate a defined signal and the interface chip will perform the signal conditioning. If the output signal changes with the specified amplitude than the sensor is working properly and the parameters of the interface chip are within the defined specifications. Output impedance describes the resistor inside the output stage of each channel. This resistor is part of a filter consisting of an external capacitor of at least 320pF and the internal resistor. Due to the high resistor level only small, inexpensive external capacitors are needed to generate low corner frequencies. When interfacing with an ADC it is important to use high input impedance input circuitries to avoid measurement errors. Note that the minimum load capacitance forms a corner frequency beyond the resonance frequency of the sensor. For a flat frequency response a corner frequency well below the resonance frequency is recommended. In general the smallest possible bandwidth for an particular application should be chosen to get the best results.
4
Functionality
The LIS3L02AQ3 is a high performance, low-power, analog output 3-Axis linear accelerometer packaged in a QFN package. The complete device includes a sensing element and an IC interface able to take the information from the sensing element and to provide an analog signal to the external world. 4.1 Sensing element A proprietary process is used to create a surface micro-machined accelerometer. The technology allows to carry out suspended silicon structures which are attached to the substrate in a few points called anchors and are free to move in the direction of the sensed acceleration. To be compatible with the traditional packaging techniques a cap is placed on top of the sensing element to avoid blocking the moving parts during the moulding phase of the plastic encapsulation. When an acceleration is applied to the sensor the proof mass displaces from its nominal position, causing an imbalance in the capacitive half-bridge. This imbalance is measured using charge integration in response to a voltage pulse applied to the sense capacitor. At steady state the nominal value of the capacitors are few pF and when an acceleration is applied the maximum variation of the capacitive load is up to 100fF. 4.2 IC Interface In order to increase robustness and immunity against external disturbances the complete signal processing chain uses a fully differential structure. The final stage converts the differential signal into a single-ended one to
5/13
LIS3L02AQ3
be compatible with the external world. The signals of the sensing element are multiplexed and fed into a low-noise capacitive charge amplifier that implements a Correlated Double Sampling system (CDS) at its output to cancel the offset and the 1/f noise. The output signal is de-multiplexed and transferred to three different S&Hs, one for each channel and made available to the outside. The low noise input amplifier operates at 200 kHz while the three S&Hs operate at a sampling frequency of 66 kHz. This allows a large oversampling ratio, which leads to in-band noise reduction and to an accurate output waveform. All the analog parameters (zero-g level, sensitivity and self-test) are ratiometric to the supply voltage. Increasing or decreasing the supply voltage, the sensitivity and the offset will increase or decrease almost linearly. The self test voltage change varies cubically with the supply voltage 4.3 Factory calibration The IC interface is factory calibrated for sensitivity (So) and Zero-g level (Voff). The trimming values are stored inside the device by a non volatile structure. Any time the device is turned on, the trimming parameters are downloaded into the registers to be employed during the normal operation. This allows the user to employ the device without further calibration.
5
Application Hints
Vdd
44
34
Figure 4. LIS3L02AQ3 Electrical Connection
Vdd
1
33
10F GND
100nF GND ST
GND
Z
LIS3L02AQ3
(top view)
23res
12
GND
1 Y
GND
22
X
FS res
res res res
11
PD
res
Optional Vout Z Cload z Optional Vout X Cload x Optional Cload y Vout Y
DIRECTION OF THE DETECTABLE ACCELERATIONS
Digital signals
Power supply decoupling capacitors (100nF ceramic or polyester + 10F Aluminum) should be placed as near as possible to the device (common design practice). The LIS3L02AQ3 allows to band limit Voutx, Vouty and Voutz through the use of external capacitors. The recommended frequency range spans from DC up to 1.5 KHz. In particular, capacitors must be added at output pins to implement low-pass filtering for antialiasing and noise reduction. The equation for the cut-off frequency
6/13
LIS 3L02AQ3
(ft) of the external filters is: 1 f t = -------------------------------------------------------------2 R o u t C l o a d ( x, y, z ) Taking in account that the internal filtering resistor (Rout) has a nominal value equal to 110k, the equation for the external filter cut-off frequency may be simplified as follows: 1.45 F f t = ---------------------------------C l o a d ( x, y, z ) The tolerance of the internal resistor can vary typically of 20% within its nominal value of 110k; thus the cutoff frequency will vary accordingly. A minimum capacitance of 320 pF for Cf(x,y,z) is required in any case. Table 6. Filter Capacitor Selection, Cf (x,y,z). Commercial capacitance value choose.
Cut-off frequency (Hz ) 1 10 50 100 200 500 Capacitor value (n F) 1500 150 30 15 6.8 3
5.1 Soldering information The QFN44 package is lead free and green package qualified for soldering heat resistance according to JEDEC J-STD-020D. Land pattern and soldering recommendations are available upon request.
7/13
LIS3L02AQ3
6
Typical performance characteristics
6.1 Mechanical Characteristics at 25C Figure 5. x-axis 0-g level at 3.3V
15
Figure 8. x-axis sensitivity at 3.3V
25
20
10
Percent of parts (%)
1.6 1.65 0g LEVEL (V) 1.7 1.75
Percent of parts (%)
15
10
5
5
0 1.55
0 0.62
0.63
0.64
0.65 0.66 0.67 sensitivity (V/g)
0.68
0.69
0.7
Figure 6. y-axis 0-g level at 3.3V
15
Figure 9. y-axis sensitivity at 3.3V
20 18 16
Percent of parts (%)
10
Percent of parts (%) 1.6 1.65 0g LEVEL (V) 1.7 1.75
14 12 10 8 6 4 2
5
0 1.55
0 0.62
0.63
0.64
0.65 0.66 0.67 sensitivity (V/g)
0.68
0.69
0.7
Figure 7. z-axis 0-g level at 3.3V
20 18 16 Percent of parts (%)
Figure 10. z-axis sensitivity at 3.3V
20 18 16 Percent of parts (%) 14 12 10 8 6 4 2
14 12 10 8 6 4 2 0 1.55 1.6 1.65 0g LEVEL (V) 1.7 1.75
0 0.62
0.63
0.64
0.65 0.66 0.67 sensitivity (V/g)
0.68
0.69
0.7
8/13
LIS 3L02AQ3
6.2 Mechanical Characteristics derived from measurement in the -40C to +85C temperature range Figure 11. x-axis 0-g level change vs. temperature
35 30 25 20 15 10 5 0 2
Figure 14. x-axis sensitivity change vs. temperature
30
25
Percent of parts (%)
Percent of parts (%)
20
15
10
5
1.5
1 0.5 Zerog level change (mg/ C)
0
0 0.025
0.02
0.015 0.01 0.005 sensitivity change (%/ C)
0
0.005
Figure 12. y-axis 0-g level change vs. temperature
35 30 25 20 15 10 5 0 1.5
Figure 15. y-axis sensitivity change vs. temperature
30
25 Percent of parts (%) 1 0.5 0 Zerog level change (mg/ C) 0.5
Percent of parts (%)
20
15
10
5
0 0.025
0.02
0.015 0.01 0.005 sensitivity change (%/C)
0
0.005
Figure 13. z-axis 0-g level change vs. temperature
30
Figure 16. z-axis sensitivity change vs. temperature
25
25
20
Percent of parts (%)
Percent of parts (%)
20
15
15
10
10
5
5
0 3.5
3
2.5
2 1.5 1 0.5 Zerog level change (mg/ C)
0
0.5
0 0.03
0.025
0.02 0.015 0.01 sensitivity change (%/C)
0.005
0
9/13
LIS3L02AQ3
6.3 Electrical characteristics at 25C Figure 17. Noise density at 3.3V (x,y axes)
35 30 16 Percent of parts (%) Percent of parts (%) 20 22 24 26 28 Noise density (ug/sqrt(Hz)) 30 32 25 20 15 10 5 2 0 18 0 0.4 0.6 0.8 1 current consumption (mA) 1.2 1.4 14 12 10 8 6 4
Figure 19. Current consumption at 3.3V
20 18
Figure 18. Noise density at 3.3V (z axis)
25
Figure 20. Current consumption in power down mode at 3.3V
30
20 Percent of parts (%)
Percent of parts (%)
25
20
15
15
10
10
5
5
0 20
30
40 50 60 Noise density (ug/sqrt(Hz))
70
80
0 1.2
1.3
1.4 1.5 1.6 current consumption (uA)
1.7
1.8
10/13
LIS 3L02AQ3
7
Package Information
Figure 21. QFN-44 Mechanical Data & Package Dimensions
mm DIM. MIN. A A1 b D E e J K L P 5.04 5.04 0.38 0.48 45 REF 1.70 0.19 0.20 0.25 7.0 7.0 0.50 5.24 5.24 0.58 0.198 0.198 0.015 0.019 45 REF TYP. 1.80 MAX. 1.90 0.21 0.30 MIN. 0.067 0.007 0.008 0.01 0.276 0.276 0.020 0.206 0.206 0.023 TYP. 0.071 MAX. 0.075 0.008 0.012 inch
OUTLINE AND MECHANICAL DATA
QFN-44 (7x7x1.8mm) Quad Flat Package No lead
M
G
M
N
34 44 44 1
33
1
DETAIL "N"
23 11
22
12
DETAIL G
SEATING PLANE
11/13
LIS3L02AQ3
8
Revision History
Table 7. Revision History
Date November 2004 May 2005 Revision 1 2 First Issue. Major datasheet review. Description of Changes
12/13
LIS 3L02AQ3
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners 2005 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com
13/13
|
